Insect Pest Control: Ants, Cockroaches, Bed Bugs and Wasps — Treatment Methods and Products Available to Professionals

Summary

Insect pests represent one of the most diverse categories in UK pest control. Ants, cockroaches, bed bugs, and wasps account for a large proportion of residential and commercial call-outs, but each requires a different approach, different products, and a different understanding of the pest's biology. What works for a common black garden ant will have no effect on a German cockroach infestation, and treating bed bugs like cockroaches — with a blanket surface spray — will disperse the infestation without eliminating it.

The UK Biocidal Products Regulation governs which insecticide active substances are approved for use, in what concentrations, and by whom. Professional pest controllers have access to formulations and concentrations that are not available over the counter. This is not just a commercial restriction — higher-concentration pyrethroids applied by an untrained operative create genuine risks to human health, non-target arthropods (particularly bees and aquatic invertebrates), and the environment. The professional use restriction exists for substantive reasons.

A key trend in UK insect pest control is the shift away from broad-spectrum residual sprays toward more targeted Integrated Pest Management (IPM) approaches. Gel bait formulations, insect growth regulators, and targeted monitoring have reduced insecticide loading in commercial kitchens and food businesses, while improving outcomes — particularly for cockroaches and bed bugs, where broad sprays historically caused repellency and exacerbated infestations. Understanding the mechanism of each treatment method is essential to selecting the right approach.

Key Facts

• Synthetic pyrethroids — the most widely used insecticide class in UK pest control; permethrin, cypermethrin, deltamethrin, lambda-cyhalothrin; act on insect sodium channels; generally low mammalian toxicity but highly toxic to aquatic invertebrates and honeybees
• Organophosphates — largely withdrawn from UK urban pest control use; pirimiphos-methyl remains approved for certain stored-product pest and crawling insect uses; high mammalian toxicity risk
• Insect growth regulators (IGRs) — methoprene, pyriproxyfen (juvenile hormone analogues); disrupt insect development; do not kill adults but prevent larvae maturing to breeding adults; effective against cockroaches and fleas
• Neonicotinoids — imidacloprid, thiamethoxam, acetamiprid; systemic action; used in gel baits for cockroaches; highly toxic to bees — never apply where bees may be exposed
• Gel bait — targeted formulation delivering insecticide in a palatable matrix; applied in cracks and crevices; reduces non-target exposure; the preferred method for cockroach control in food businesses
• Residual spray — liquid insecticide applied to surfaces where insects walk; provides a period of kill lasting days to weeks depending on product and surface
• Knockdown spray — fast-acting aerosol for immediate kill; typically pyrethrin-based; no residual effect; used for direct application to visible insects
• Dusts — diatomaceous earth or insecticidal dust (e.g. bendiocarb dust); applied to voids, roof spaces, and other inaccessible areas; long residual; effective for ants in cavity walls
• ULV (Ultra Low Volume) treatment — nebulisation of insecticide for flying insect control in enclosed spaces; requires evacuation and re-entry intervals
• Bed bug resistance — pyrethroid resistance is widespread in UK bed bug populations (Cimex lectularius); spray treatments alone are often ineffective; heat treatment or combined approaches are more reliable
• German cockroach (Blattella germanica) — the most common UK cockroach pest; strongly associated with food businesses and residential flats; requires gel bait and IGR treatment; highly resilient
• Oriental cockroach (Blatta orientalis) — less common; prefers cooler, damper environments; found in basements and drains; more susceptible to residual spray
• Common wasp (Vespula vulgaris) and German wasp (Vespula germanica) — the two most common UK stinging insects; nests built annually; queens overwinter; treated with insecticidal dust or spray applied to nest entrance

Quick Reference Table

Detailed Guidance

Ant Control

The most common UK ant pest is Lasius niger, the common black garden ant. It nests outdoors and forages inside buildings seeking sweet and protein-based food. Treatments that kill foraging workers without eliminating the queen have no lasting effect — queens must be eliminated for a lasting result.

Gel bait is the most effective approach for indoor infestations. Ants collect the bait and return it to the nest, where the queen and brood are killed by secondary exposure. Advion Ant Gel (indoxacarb) is the leading professional product. It must be applied in small amounts (approximately 0.5g per application point) at intervals of around 15cm along ant runs. Applying too much bait or placing it on surfaces where it has been contaminated by cleaning products will reduce uptake.

Residual spray to ant runs and entry points using cypermethrin or permethrin-based products provides knockdown and short-term residual kill. It does not eliminate the nest. Outdoor application must be made when bees are not active (early morning or evening) and not to flowering plants. Proximity to water features and drains must be considered — synthetic pyrethroids are highly toxic to aquatic life at very low concentrations.

External granule bait (e.g. Ant Killer Granules with indoxacarb, professional formulation) can be applied around nest entrances and along external runs. This is a slow-kill bait that allows nest elimination via secondary transfer.

Pharaoh ants (Monomorium pharaonis) are a separate species and a more serious pest — they are associated with hospitals and heated buildings, form multiple colonies, and respond adversely to spray treatments (which cause colony splitting). Pharaoh ant infestations require specialist treatment with targeted protein-based bait and thorough surveying.

Cockroach Control

Cockroach control in commercial food environments is one of the most technically demanding challenges in UK pest control. German cockroaches in particular are highly resilient, reproduce rapidly (one female can produce several hundred offspring in a lifetime), and have developed resistance to multiple insecticide classes including pyrethroids, organophosphates, and some neonicotinoids.

Gel bait is the first-line treatment for German cockroaches in food areas. It is applied in small dots (0.5–1g) at 15–20cm intervals in cracks and crevices — behind equipment, under appliances, inside electrical units (with power isolated). The bait attracts cockroaches through feeding stimulants and delivers a lethal dose of insecticide. Bait must be rotated between active substances to prevent resistance development. Never apply repellent insecticide sprays near gel bait — this disrupts cockroach movement and reduces bait uptake.

Insect growth regulators (IGRs) such as hydroprene (Gentrol) are applied as a supplement to bait treatment. They prevent nymphs from developing into reproductive adults, effectively breaking the breeding cycle. IGRs are not lethal to adults but significantly reduce population growth rates.

Monitoring using sticky monitors placed at harbourage sites quantifies the population and tracks treatment progress. Monitor catches at each visit provide objective evidence of infestation reduction and inform treatment decisions.

Residual spray (deltamethrin, cypermethrin) is not the preferred primary treatment for German cockroaches in food areas but may be used in non-food areas or as a supplementary perimeter treatment. It must never be applied to surfaces where food is prepared or where bait has been applied.

Oriental cockroaches are less resistant and respond better to residual spray treatments, but harbourage identification and drain inspection are critical — oriental cockroaches are frequently sourced from drain systems.

Bed Bug Control

Bed bugs (Cimex lectularius) are one of the most challenging insect pests encountered in UK residential and hospitality settings. They are obligate blood feeders, hiding in mattress seams, bed frames, headboards, skirting boards, and electrical sockets during the day and emerging to feed at night. They can survive for months without feeding.

Pyrethroid resistance is widespread in UK bed bug populations. Many infestations will not respond adequately to pyrethroid-based sprays alone. Professional pest controllers should assume resistance unless resistance has been specifically ruled out, and plan treatment accordingly.

Heat treatment — raising the room temperature to a lethal minimum of 50–55°C for a sustained period — kills all life stages of bed bugs including eggs, which are resistant to most insecticides. Commercial heat treatment equipment is used by specialist pest controllers. It is expensive and disruptive but can resolve an infestation in a single treatment where spray-based approaches require multiple visits.

Cryonite (CO2 freeze treatment) uses liquid CO2 delivered at -78°C to freeze and kill bed bugs on contact. It is effective for spot treatments on mattresses, headboards, and furniture that cannot be treated with chemicals.

Combined chemical approach: Where heat or cryonite is not used, a combination of a residual non-repellent spray (Temprid SC — imidacloprid and beta-cyfluthrin — is widely used by UK professionals), a residual pyrethroid dust to voids and skirting boards, and a monitoring programme provides the best chemical outcome. Multiple visits at 2-week intervals are typically required.

Preparation by the occupant before treatment is essential — washing and heat-drying bedding, clearing clutter from around the bed, and ensuring access to all areas. Inadequate preparation is the single most common cause of bed bug treatment failure.

Wasp Nest Treatment

Wasps nests in the UK are annual structures — they are established by a queen in spring, grow through summer, and the colony dies out in autumn. The nest should not be disturbed without treatment; a single nest may contain 3,000–8,000 workers by late summer.

Treatment approach: Insecticidal dust (bendiocarb dust — Ficam D is the professional standard product) is the most effective treatment method. The dust is applied directly into the nest entrance, typically using a puffer applicator or extension lance. Workers carry the dust into the nest, causing colony collapse within 24–48 hours. Treatment is most safely carried out at dusk when foragers have returned to the nest.

Where the nest entrance is not accessible (cavity walls, underground nests), a residual insecticide can be applied around the entrance, or a specialist access point can be created. Foam-based treatments are available for cavity wall nests.

Risk of stings: Wasps are not aggressive away from the nest but will defend the nest vigorously. Operatives should wear a bee/wasp suit or at minimum a full coverall, veil, and gloves. An adrenaline auto-injector (EpiPen) should be carried by all operatives treating wasps due to the risk of anaphylaxis.

Honey bee nests — it is important to identify whether a nest contains wasps or honey bees before treatment. Honey bees are beneficial pollinators and should not be destroyed where avoidance or rehoming is possible. If in doubt, contact a local beekeeper through the British Beekeepers Association (BBKA). Destroying a honey bee colony is not illegal but professional pest controllers are expected to recommend alternatives first.

Frequently Asked Questions

Can I use professional-strength insecticides on a DIY basis?

No. Products containing higher concentrations of active substances — for example, deltamethrin at 2.5% w/v or cypermethrin at 25% w/v — are restricted to professional use under their UK BPR approvals. Consumer products are available at lower concentrations (typically 10–25 times lower) and with restricted application methods. Using a professional product without appropriate training is unlawful and creates genuine health and environmental risks.

Why don't surface sprays work well for German cockroaches?

German cockroaches have developed resistance to most synthetic pyrethroids and some organophosphates. Additionally, surface sprays are repellent — they discourage cockroaches from crossing treated surfaces, which may temporarily reduce visible activity without eliminating the infestation. Gel bait works through a different mechanism (attraction rather than repulsion) and is therefore more effective in resistant populations.

How many visits are typically needed to eliminate a bed bug infestation?

For chemical treatment, a minimum of two visits at 2-week intervals is standard, with three or four visits required for heavier infestations. Heat treatment can achieve resolution in a single visit if carried out correctly, but a follow-up inspection 2–4 weeks later is advisable. Complete elimination should be confirmed by the absence of live bugs and new bites, not just reduced visible activity.

Are all wasps treated the same way?

Common wasps (Vespula vulgaris) and German wasps (Vespula germanica) are treated identically — insecticidal dust to the nest entrance. Hornet nests (Vespa crabro — European hornet, now present across much of southern England) are treated similarly but require additional caution due to larger body size and more aggressive nest defence. Asian hornets (Vespa velutina) are a notifiable invasive species — sightings must be reported to the Great Britain Non-Native Species Secretariat (NNSS); professional treatment requires coordination with local authorities.

Is pyrethroid insecticide safe to apply indoors?

Most synthetic pyrethroid products approved for indoor use have low mammalian toxicity at label application rates. The principal risks from indoor pyrethroid application are: inhalation of spray mist during application (mitigated by PPE and ventilation); aquatic contamination if the product reaches drains; and toxicity to cats, which have limited ability to metabolise pyrethroids. Occupants and pets should vacate treated areas until surfaces are dry, and the re-entry interval stated on the product label must be observed.

Regulations & Standards

• UK Biocidal Products Regulation (UK BPR) — product types PT18 (insecticides, acaricides) and PT19 (repellents); governs approval of all insecticide products; professional use restrictions apply to many active substances and formulations

• Control of Substances Hazardous to Health Regulations 2002 (COSHH) — risk assessments required for all insecticide applications

• The Invasive Alien Species (Enforcement and Permitting) Order 2019 — Asian hornet (Vespa velutina) is listed on Schedule 9 of the Wildlife and Countryside Act as amended; sightings must be reported

• Health and Safety at Work etc. Act 1974 — general duty of care to employees and members of the public during pest control operations

• Food Safety and Hygiene (England) Regulations 2013 — pest control in food businesses must be carried out to a standard that protects food from contamination; insecticide use must comply with product label food-area restrictions

• HSE Pesticides — UK BPR Product Type 18 (Insecticides) — regulatory framework for insecticide products

• BPCA Pest Identification and Treatment Guides — practical guidance on common UK insect pests

• Asian Hornet Action Team — GB Non-Native Species Secretariat — reporting and identification guidance for Asian hornets

• British Beekeepers Association (BBKA) — Honey Bee Swarm and Nest Information — referral point for suspected honey bee nests before pest control

• COSHH Essentials for Pest Control — HSE — online tool for assessing COSHH risks from pest control products

• bpca membership certification — professional qualifications and competency requirements

• coshh in pest control — COSHH risk assessments for insecticide handling and PPE

• rodent control rats and mice — rodent control methods and legal requirements

• bird pest control — managing pest bird species